Thermostat switch means having frictionless contact actuator



7 July 6, 1965 K. R. UHLICH 3,193,649

THERMOSTAT SWITCH MEANS HAVING FRICTIQNLESS CONTACT ACTUATOR Filed July 13, 1962 I 5 INVENTOR:

- Karl U/i/ic/z United States Patent 3,193,649 THERMOTAT SWITCH MEANS HAVING FRICTKONLESS CGNTACT ACTUATOR Karl R. Uhlich, Mansfield, Uhio, assignor to Pace, Inc, Mansfield, Ohio, a corporation of Ghio Filed July 13, 1962, Ser. No. 2tl9,5ti1 6 Claims. (Cl. 200-138) This invention relates to switch mechanisms and more especially to an adjustable switch mechanism embodying thermoresponsive control means for a circuit of a current consuming instrumentality with which the switch mechanism may be utilized.

Switch mechanisms of this general character embodying thermoresponsive'means for controlling the temperature of heating elements or current consuming instrumentalities have heretofore incorporated an insulating means associated with a thermoresponsive means or element cooperating with a switch arm or contact carrying member, such arrangement being utilized through fiexure or relative movement of the thermoresponsive means under the influence of temperature variations for controlling an electric circuit.

. It has been a practice to utilize a pin or strut member such as shown in HutImanPatent 3,004,124 provides only a point contact with the thermo-controlled element which, being flexible, may be rendered unstable by reason of friction between the point and the element or, due to inaccuracies in manufacture, wherein the point of contact of the strut member with the thermoresponsive element is not properly centered. Any out-of-center inaccuracy of the strut member-with respect to the resilient or toggle means for securing the snap action sets up transverse flexure of the snap action element which impairs the operation thereof and hence afiects the accuracy of the automatic control through the thermoresponsive means.

The present invention embraces a switch mechanism of the-thermoresponsive or thermostat type embodying an insulating membenor strut disposed between the thermoresponsive means and a relatively movable component of v the switch mechanism whereby a rectilinear edge or line contact is established between the strut member and the resilient means whereby transverse fiexure or distortion of the component is prevented.

Another object of the invention resides in the provision of an insulating strut member disposed between a bimetallic element and a resilient or relatively movable compo- ,nent actuated thereby embodying a configuration at the region of engagement of the strut member with the component to reduce friction to a minimum and at the same time provide for stability of operation and wherein slight inaccuracies in centering the strut member with respect to the component do not impair the operation of the thermoresponsive control means of the switch mechanism.

Another object of the invention resides in the provision of a thermostat type of switch mechanism incorporating a rigid insulating member between a thermoresponsive element and a resilient or relatively movable component of the switch mechanism providing a bearing contact of substantial length but of a minimum :area whereby the 3,193,649 Patented July 6, 1965 thermoresponsive means of control for a switch member is accurate and reliable in operation.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operration and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

FIGURE 1 is an enlarged longitudinal sectional view of a form of thermostat switch mechanism embodying the invention;

FIGURE 2 is a transverse sectional view taken substantially on the line 2-2 of FIGURE 1;

FIGURE 3 is an enlarged fragmentary plan view showing a portion of the thermoresponsive element and the strut member of the invention;

FIGURE 4 is a view of the strut member and a relatively movable member of the switch mechanism illustrating the character of bearing engagement between these members; I

FIGURE 5 is a detail sectional view taken substantially on the line 5-5 of FIGURE 3; 7

FIGURE 6 is an end view of the construction illustrated in FIGURE 3;

FIGURE 7 is a fragmentary sectional view similar to FIGURE 5 illustrating a modified form of insulating strut member, and

FIGURE 8 is a bottom plan view of the construction illustrated in FIGURE 7.

The switch mechanism embodying the invention is particularly adaptable for thermostatically controlling the energization of any current-consuming instrumentality subject to temperature variations and may be utilized for controlling heating units, air conditioning equipment, refrigeration units or controlling a circuit of a variable temperature unit where it is desirable to obtain a thermostatically controlled action to make or break the circuit.

While the form of thermostat switch means illustrated is of the type embodying a toggle or snap action for rapidly making or breaking a circuit, it is to be understood that the invention may be used with thermostat type switches wherein the thermoresponsive means actuates a current conducting member to make and break a circuit without snap action.

Referring to the drawing in detail, and initially to FIGURE 1, there is illustrated a frame portion 10 of an appliance embodying an electrically energizable heating or variable temperature unit. For purposes of illustration, the switch means is in the circuit of an electrically energizable heating element or component 12, shown schematically, to which electric energy may be supplied through supply conductors or power lines L1 and L2, the switch means being intercalated in the power line L2.

The switch mechanism illustrated in FIGURES 1 and 2 is enlarged to :about twice actual size. The switch mech ,anism is inclusive of a frame construction provided by a plate component or member 14 and a tubular component or sleeve 16, the plate 14 being formed with an opening to receive a tenon formed on one end of the sleeve 16. The sleeve provides support for several elements of the switch means assembled in stacked relation, the plate 14 providing a support for :a manually adjustable means of the switch mechanism.

The opposite end region of the sleeve is formed with a flange 18. After assembly of several components of the switch mechanism carried by the sleeve, the end region of the sleeve 16 is swaged or staked as at 20 so as to maintain the several components in assembled relation.

The sleeve component of the frame construction may be secured to the frame 16 of an appliance and a housing portion 21 of the appliance by a bolt 22 and a securing nut 24. l

The form of switch construction illustrated includes manually adjustable means operable within the operating temperature range of the switch for manually adjusting or modifying the'relative position of one of the switch arms or current conducting members, a thermoresponsive means being provided to maintain substantially constant the temperature for which the manual means is adjusted. The frame plate 14 is provided with an opening to snugly receive a tenon formed on a sleeve or fitting 26, a portion of the tenon being swaged as shown at 27 over the adjacent region of the plate 14 to secure the sleeve to the plate. I

The fitting 26 is interiorly threaded to accommodate a threaded member or shaft 36, the shaft being provided with a tenon 31 to receivea manipulating knob or grip member (not shown) of conventional construction for rotating the shaft 30. A pin 32 projecting from the tenon portion 31 is adapted for cooperation with an abutment or stop means 34 to define the limits of rotation and hence the temperature range within which the switch is adapted to operate.

The switch mechanism is inclusive of a first switch arm or current conducting member 36 carrying a contact 3S and a second switch arm or current conducting member 46 carrying a contact 42.

The switch mechanism includes a current conducting flexible or spring support member 44 and a thermoresponsive means or bimetallic element 46. The switch members, 36 and 40, the member 44 and terminals or connectors 48 and 59 are insulatingly supported by insulating means mounted on the frame component or sleeve 16. I

The switch members 36 and 4t) and the spring support member 44 are provided throughout a portion of their lengths with spaced parallel ridges which terminate at.

a region spaced from the support means to provide a "flexing or fulcrum region for each of these members adjacent the support. The switch members 36 and 4t and the spring support member 44 are insulatingly supported by ceramic or lava insulating washers or members 52, 53 and 54 nested or stacked on the sleeve 16. The bimetallic element 46 is provided with an opening toaccommodate the sleeve 16 and is supported thereby adjacent the flange 18. V V

The relative position of the first switch arm or member 36 is controlled by the manually rotatable shaft 36. A member or pin 56 formed of insulating material, such as ceramic or lava, is contained in a socket or recess formed in the shaft 30, the lower end of the pin engaging the first switch arm 36, this switch. arm being inherently flexed or biased in an upward direction whereby rotation 'of the shaft 30 changes the relative position thereof upwardly or downwardly dependent upon the direction of rotation of the shaft to adjust the position of the switch arm in accordance with a temperature to be maintainedr The thermoresponsive means or element 46 is fashioned of two intimately joined metal layers, the metals having dissimilar coefficients of expansion whereby variations in the ambient temperature cause flexing or rela tive movement of the bimetallic element or thermoresponsive means 46. The element 46 is provided at its distal end with an insulating member or strut 60 which forms a feature of the present invention and will hereafter be described in further detail. The strut 60 is adapted forengagement with a resilient means or component 62 which is anchored to the spring support or member 44. I

The resilient means 62 is associated with the relatively movable switch member 40 and the support member 44 in a manner establishing a snap action effective to rapidly engage and disengage the contacts 36 and 42. The

resilient means 62 is of the character disclosed in Huffman Patent 3,004,124 and is fashioned with a planar or flat portion 64 and a curved or arcuately-shaped portion 66. The planar portion 64 is welded or otherwise fixedly joined to the current conducting support member or means 44. The member 44 is provided with a struckup projection 63 providing a stop means or abutment for limiting the downward fiexure of the switch arm 40 when the contacts 38 and 42 are disengaged.

The distal end region of the arcuate or curved portion '66 is provided with a slot or opening to receive a pro jection 7t) integrally formed on the distal end of the switch arm 48.

The region adjacent the juncture of the arcuate portion 66 with the planar portion 64 is fashioned with an opening (not shown) providing an area of reduced crosssection or a weakened Zone functioning as a hinge to facilitate flexure of the arcuate portion 66 during movements of the switch arm 40. This arrangement provides for a snap action initiated by movements of the bimetallic element 46 under the influence of temperature variations.

Thus under the influence of movements of the bimetallic element 46, the arcuate portion 66 will be actuated about its hinge or weakened zone and moved upwardly or downwardly depending upon the direction of movement or flexure of the bimetallic element 46. Through thismeans a toggle action is provided for imparting movement to the switch arm or member 40 to effect engagement or disengagement of the contacts 38 and 42 for automatically controlling the circuit to the currentconsuming instrumentality dependent upon temperature variations influencing the position of the bimetallic element 46.

In the embodiment illustrated, the thermoresponsive means 66 is arranged to be flexed upwardly by increased ambient temperature, the strut 60 engaging the portion 64 effects a flexing of the planar portion upwardly to a position wherein the toggle action of the curved portion 66 imparts a downwardly acting pressure on the arm 40 with a rapid or, snap action to disengage the contacts without appreciable arcing;

When the ambient temperature is reduced, the strut 60 moves away from the portion 64 and the inherent stress in the portion 64 flexes the curved portion 66 upwardly with a snap action to re-engage contacts 38 and 42 to complete a circuit.

The distal end region of the switch arm or member 36 is provided with a fitting 74 which is interiorly threaded to receive a threaded member 76 and which may be adjusted by insertion of a suitable tool in a kerf provided in the member 76.

The opposite end of the member 76 is provided with a recess'accommodating one end of a strut 78 of lava, ceramic or other insulating material which extends through a clearance opening 80 in the switch member 40, the lower end engaging the upper surface of the spring support member 44. By rotating the threaded member 76 relative to the fitting 74, the distance between the switch member 36 and the spring support or member 44 may be regulated. This adjustment varies the maximumspaeing between the contacts 38 and 42 in disengaged relation and in a measure controls or regulates the sensitivity of the toggle action of the curved spring 66.

The strut member 60 carried by the bimetallic element 46 is of a particular configuration. As particularly shown in FIGURES 3 through 6 the strut member 60 comprises a circular body portion 84 fashioned with convergingly arranged curved surf-aces 86 which, at their region or apex of convergence, provide a rectilinear bearing, ridge or edge 88 which, as illustrated in FIGURES 1 and 2, extends transversely of the longitudinal axis of the switch mechanism. The edge 88 provides a rectilinear bearing region or line engagement with the planar portion 64 of the resilient means 62.

The body portion 84 is provided with a shoulder or ledge 90 and a tenon portion 92, the latter extending through an opening formed in the bimetallic element or thermoresponsive means 46, the ledge or shoulder 90 seating on the upper surface of the element 46. Fitted over the tenon portion 92 is a spring retainer, locking means or lock washer 94 of conventional construction adapted to secure the strut to the bimetallic element.

Through this arrangement a line contact is provided by the edge 88 for engagement of the strut with the planar portion 64 of the resilient means 62. The knife edge 88, extending transversely of the longitudinal axis of the member 64, provides a comparatively long bearing of small .area in a transverse direction so that upon upward movement or fiexure of the bimetallic element 46, the strut effects fiexure of the resilient means 62 in a manner to prevent transverse distortion of member 62 which would otherwiseimpair the operation of the resilient means.

Thus the center of the strut 60 does not have to be accurately located with respect to the central axis of the planar portion 64 as the rectilinear bearing contact provided by the edge or ridge 83 prevents any twisting of the resilient means 62. Furthermore through the use of a linear bearing area provided by the edge 88 the frictional engagement between the strut and the planar portion 64 is at a minimum so that there is no appreciable frictional drag of the strut on the means 62 and hence promoting a higher degree of sensitivity of operation of the toggle or snap action provided by the resilient means 62.

The body of the insulating strut 60 may be of noncircul'ar cross-section but the converging surfaces should be shaped to provide the rectilinear bearing region hereinbefore described.

FIGURES 7 and 8 illustrate a modified form of the construction shown in FIGURES 3 through 6. In this a form the insulating strut 1G0, mounted upon the bimetallic element 46', is fashioned with a pair of planar converging surfaces 102, the apex 104 of which provides a rectilinear edge or bearing for engagement with the member 64 of the thermoresponsive means in the same mannor as illustrated in FIGURE 4.

The strut member 100 is fashioned with a tenon 106 which projects through an opening in the bimetallic element 46' and is securely anchored to the element by means of a retainer or lock washer 94' of the same construction as that illustrated at 94 in FIGURES 5 and 6. The strut 100 is fashioned of lava or ceramic or other rigid high temperature resistant insulating material.

In the operation of the switch mechanism in controlling an appliance or region of variable temperature, the shaft 30 is rotated to a position at which a desired temperature for the current consuming instrumentality is to be maintained which movement is transmitted to the member 36 predetermining the position of said member and the member 44. When the ambient temperature increases by heat from the energized instrumentality, the bimetallic element 46 is flexed upwardly as viewed in FIGURE 1 moving the strut 60 upwardly to engage the rectilinear bearing area 83 with the planar portion 64 of the resilient means 62.

The upward pressure of the bimetallic element is transmitted to the resilient means 62, flexing the planar portion upwardly effecting movement of the curved portlon 66 to direct a force against the switch arm 40. When the resilient means 62 is flexed to an extent that the force exerted thereby against the switch arm 4!) causes a hinging movement of the curved portion 66 about the weakened region, the switch member 40 is flexed downwardly to disengage the contacts, the resilient means 62 providing a toggle-like snap action to rapidly separate the contacts.

When the ambient temperature affecting the thermoresponsive means 46 is reduced, the means is flexed downward-1y permitting downward movement of the planar portion 64 of the resilient means which, at a certain point in its movement causes, a rocking or hinging of the curved portion 66 to direct an upward force on the switch arm 40 to again re-engage the contacts 38 and 42 and c mplete the energizing circuit. It should be'noted that the spring support or actuating member 68 and the resilient means 62 are current-conducting members as they are in contact with the switch member 40.

Through the utiliziation of the forms of strut arrangement hereinabove described, a highly sensitive and accurate thermoresponsive control is provided which, through the snap action provided by the resilient means 62, maintains stabilized operation of automatic control for an appliance or inst-rumentality with a high degree of sensitivity.

The arrangement provides for sensitive and reliable control irrespective of whether the central axis of the strut member is coincident with the longitudinal axis ofthe planar portion 64 of the resilient means 62.

It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than as herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

I claim:

1. Apparatus of the character disclosed, in combination, switch means including relatively movable current-conducting member's, thermoresponsive means comprising a strip formed of dissimilar metals, an insulating member supported on said strip and arranged to effect movement of one of said current-conducting members upon variations in temperature, retaining means for securing the insulating member to the strip, said insulating member being fashioned with convergingly arranged surfaces, the region of convergence providing a rectilinear bearing for engagement with the member arranged to be moved by the thermoresponsive means.

2. Apparatus of the character disclosed, in combination, switch means having relatively movable switch arms, a relatively movable member for influencing the position of one of the switch arms, thermoresponsive means, a rigid insulating strut secured to said strip and arranged t effect movement of said member upon variations in temperature, said insulating strut being fashioned with convergingly arranged surfaces, the region of convergence providing a knife edge bearing for engagement with the relatively movable member.

3. Apparatus of the character disclosed, in combination, switch means comprising relatively movable current-conducting members, manually operable means for controlling the relative position of one of said members, thermoresponsive means comprising a strip formed of dissimilar metals for controlling the relative position of another of said members, said strip having an opening formed therein, a rigid insulating strut having a portion extending into the opening, means securing the insulating strut to the strip, said insulating strut having a body portion fashioned with convergingly arranged surfaces, the region of convergence of said surfaces forming a rectilinear bearing adapted for engagement with the member controlled by the thermoresponsive means.

4. Apparatus of the character disclosed, in combination, switch means comprising relatively movable current-conducting members, manually operable means for controlling the relative position of one of said members, thermoresponsive means comprising a strip formed of dissimilar metals and having an opening therein,'a resilient element having a planar portion and a curved portion, said curved portion having pivotal connection with another of said members, a rigid insulating strut having a shank portion extending through the opening in the strip, means engageable with the shank portion securing the strut to the strip, said insulating strut being fashioned with convergingly arranged surfaces, the region of the convergence of said surfaces forming a rectilinear bearing area adapted for engagement with the planar portion of the resilient element whereby fiexure of the resilient element under the I prising a strip formed of dissimilar metals andhaving an opening therein at a region spaced from thes-upport, a rigid member formed of insulating material mounted on the strip and having a shank portion extending through the opening in the strip, a retaining clip secured 'to the shank portion of the insulating member securing the insulating member to the strip, said member being formed ,With convergingly arranged surfacesthe region of convergence of' said surfaces providing a rectilinear edge configuration. i

6. In combination, a support, a thermoresponsive means carried by the support, said thermoresponsive means com prising a 'un-it formed of dissimilar metals, said unit having an opening formed therein at a. region spaced from the support, a member formed of insulating material having a body portion and a shank portion, the shank portion adapted to extend through the opening in the unit and the body portion engaging the unit, retaining means engageable Wtih the shank portion securing the member to the unit, said body portion being formed with c nvergingly arranged curved surfaces, the region of convergence of said curved surfaces forming a rectilinear edge configuration.

References Cited by the Examiner UNITED STATES PATENTS 1,799,651 4/ 31 Siegmund 200--166 2,899,520 8/59 McCreary 200166 2 ,906,840 9/59 Ulanet 200-113 3,004,124 10/61 Huffman 200 -138 3,068,335 12/62 Gregg 200-466 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCI-IAEFER, Examiner. 

1. APPARATUS OF THE CHARACTER DISCLOSED, IN COMBINATION, SWITCH MEANS INCLUDING RELATIVELY MOVABLE CURRENT-CONDUCTING MEMBERS, THERMORESPONSIVE MEANS COMPRISING A STRIP FORMED OF DISSIMILAR METALS, AN INSULATING MEMBER SUPPORTED ON SAID STRIP AND ARRANGED TO EFFECT MOVEMENT OF ONE OF SAID CURRENT-CONDUCTING MEMBERS UPON VARIATIONS IN TEMPERATURE, RETAINING MEANS FOR SECURING THE INSULATING MEMBER TO THE STRIP, SAID INSULATING MEMBER BEING FASHIONED WITH CONVERGINGLY ARRANGED SURFACES, THE REGION OF CONVERGENCE PROVIDING A RECTILINEAR BEARING FOR ENGAGEMENT WITH THE MEMBER ARRANGED TO BE MOVED BY THE THERMORESPONSIVE MEANS. 